Box Body Roof Modification Questions

[mercurygm88]

I don't actually have possession of the car yet, so I don't know. But from all of the photos of boxes with coach roofs, it sure looks like the angle of the rear window is steeper than a standard roof. Also, the C-pillar on the coach roof boxes looks wider at the top than the standard roof C-pillar. That's why I was assuming that the roof was extended rearward a few inches on the coach roof boxes.

In fact, when I look at the photos of your car taken from the side, where the C-pillar is visible, and I compare them to a non-coach roof car, the shape of the C-pillar looks drastically different to me. That is, the C-pillar on coach-roof cars looks like it's nearly constant width all the way up, whereas, on non coach roof cars, the C-pillar tapers markedly from bottom to the top.

I guess one way to know for sure is to measure the top of the C-pillar on a coach roof car and compare to a non coach roof car. But, since I don't have access to the coach roof car, I can't measure it.

However, I do have a non-coach roof car. When I measure from the top, rear corner of the rear door molding straight back to the corner of the roof, measures right at 10 inches.

If I remember I'll go out and measure mine tomorrow but I can tell you for sure that it does taper smaller towards the top.

[TomO]

I'm going to try to post two pictures. One is a right side view of a coach roof and the other is a right side view of a non-coach roof. I've drawn red lines on the perimeter of the C-pillar on each photo. If you compare the shape of the C-pillars, you can see that they are different. The top of the coach roof is longer and the rear window is more vertical than the non-coach roof.

[88Vic]

It would still look better than a vinyl roof in my opinion, mine I think is starting to crack since I don't have a garage to store my car in an most of the time it sits in the sun.

[mercurygm88]

I'm going to try to post two pictures. One is a right side view of a coach roof and the other is a right side view of a non-coach roof. I've drawn red lines on the perimeter of the C-pillar on each photo. If you compare the shape of the C-pillars, you can see that they are different. The top of the coach roof is longer and the rear window is more vertical than the non-coach roof.

It does look as though mine has a slightly longer roof but it may also just be an optical illusion ill have to measure it when I get the chance. (hopefully tomorrow P.M. me and remind me if you have too)

[TomO]

If I remember I'll go out and measure mine tomorrow but I can tell you for sure that it does taper smaller towards the top.

Thanks. Yes, from what I see, the rear window of the coach roofs are steeper and the C-pillar is more square than the non-coach roofs.

That tells me that since the bottom of the rear window in both coach and non-coach is in the same spot (right next to the trunk opening) the upper part of the coach roof must be longer than the non-coach roof. So, there must be some sort of structure that is added on to the standard roof to make it longer.

I have a vague recollection of seeing a coach roof car with the vinyl removed and you could see that there was some sort of white fiberglass or plastic piece attached to the standard roof that makes the upper rear edge of the coach roof extend rearward for at least several inches.

[TomO]

It would still look better than a vinyl roof in my opinion, mine I think is starting to crack since I don't have a garage to store my car in an most of the time it sits in the sun.

I think it depends on what you're looking for. If you have basic handiwork skills you could do a basic slicktop conversion yourself. I did one on my '89 Grand Marquis, but it was just a standard, all metal roof under the vinyl. Most cars actually have a nice coat of paint under the vinyl. The trick is (after removing the vinyl) to get all the glue off. I did it using a heat gun and plastic putty knife to get most of it off, then use acetone to get the rest off. Then you might want to fill the roof weld seams. I used lots of layers of fiberglass mat to fill mine, followed with bondo filler. You'll also need to fill the holes in the roof if you remove the trim at the front of the vinyl. There are lots of ways to do this. The simplest way is to get some small rubber expandable plugs. They look like an upside down top hat and they have a threaded insert in them. You put a small machine screw in the insert and when you tighten it, the plug expands. You may have to drill the hole out a bit. Go with the smallest plugs that will still fit. That way they won't be very noticeable.

That, of course is the cheap and dirty way. You can also fill them, but then you'd also have to sand and repaint most of the roof.

[mercurygm88]

I like my vinyl top and after 24 years its still like new albeit a little dirty. I go over it once a month in the warmer weather with a vinyl protectant/conditioner. Regardless of the fact that I am a full grown man if it ever starts to crack I will cry.

[TomO]

I like my vinyl top and after 24 years its still like new albeit a little dirty. I go over it once a month in the warmer weather with a vinyl protectant/conditioner. Regardless of the fact that I am a full grown man if it ever starts to crack I will cry.

Yes, your vinyl looks like it's in excellent condition. When I got my car, it was 20 years old and in excellent condition, even the paint looked new -- except for the vinyl top. It was really dried out and brittle. It didn't take long for it to start shredding, and it got lots of holes in it, so I had to remove it.

So, yes, it appears that regular application of conditioner will really help preserve the vinyl.

[jaywish]

Maybe call a glass shop and ask?

Jay

[TomO]

Maybe call a glass shop and ask?

Jay

That's an idea, but I seriously doubt the glass shop will know what I'm talking about in regard to removing whatever it is that makes the coach roof different from the standard roof -- especially considering that fact that even the box-body enthusiasts on this site aren't really sure.

I'm mainly wondering if it's possible to do the conversion from coach roof to non coach roof, and if so, what it entails.

If it's possible to get a coach roof to where it's the same as a standard rear window, then it seems like a glass shop should theoretically be able to install a gasket and window glass. But, I don't know if the standard body is cut or somehow permanently modified when the coach roof is installed.

Anyhow, maybe I will call a glass shop or two and ask -- I guess it couldn't hurt.

[88Vic]

I think it depends on what you're looking for. If you have basic handiwork skills you could do a basic slicktop conversion yourself. I did one on my '89 Grand Marquis, but it was just a standard, all metal roof under the vinyl. Most cars actually have a nice coat of paint under the vinyl. The trick is (after removing the vinyl) to get all the glue off. I did it using a heat gun and plastic putty knife to get most of it off, then use acetone to get the rest off. Then you might want to fill the roof weld seams. I used lots of layers of fiberglass mat to fill mine, followed with bondo filler. You'll also need to fill the holes in the roof if you remove the trim at the front of the vinyl. There are lots of ways to do this. The simplest way is to get some small rubber expandable plugs. They look like an upside down top hat and they have a threaded insert in them. You put a small machine screw in the insert and when you tighten it, the plug expands. You may have to drill the hole out a bit. Go with the smallest plugs that will still fit. That way they won't be very noticeable.

That, of course is the cheap and dirty way. You can also fill them, but then you'd also have to sand and repaint most of the roof.

The problem is that I have a Town Car, so mine has the fiberglass shell and a smaller rear window. I'd have to do all that plus install a completely different window. I can do a lot of automotive work myself but I have no bodywork experience at all, and i'm not about to practice on my Lincoln (I can get an old minivan or accord for that). I need to really inspect how bad it is, I may be able to save it by using a vinyl protector, it's not what I ultimately want but it would save me a ton of trouble. I could go the route of dying the roof to match whatever paint I choose, although the vinyl does have to come off to get the rear window out to get it re-tinted, so it's all still up in the air.

[86VickyLX]

The problem is that I have a Town Car, so mine has the fiberglass shell and a smaller rear window. I'd have to do all that plus install a completely different window. I can do a lot of automotive work myself but I have no bodywork experience at all, and i'm not about to practice on my Lincoln (I can get an old minivan or accord for that). I need to really inspect how bad it is, I may be able to save it by using a vinyl protector, it's not what I ultimately want but it would save me a ton of trouble. I could go the route of dying the roof to match whatever paint I choose, although the vinyl does have to come off to get the rear window out to get it re-tinted, so it's all still up in the air.

You have full vinyl or half vinyl?

[TomO]

The problem is that I have a Town Car, so mine has the fiberglass shell and a smaller rear window. I'd have to do all that plus install a completely different window. I can do a lot of automotive work myself but I have no bodywork experience at all, and i'm not about to practice on my Lincoln (I can get an old minivan or accord for that). I need to really inspect how bad it is, I may be able to save it by using a vinyl protector, it's not what I ultimately want but it would save me a ton of trouble. I could go the route of dying the roof to match whatever paint I choose, although the vinyl does have to come off to get the rear window out to get it re-tinted, so it's all still up in the air.

Yeah, I can definitely understand where you're coming from. It sounds like your car is something you want to keep in original condition or at least close to it.

Mine was in good shape, but I didn't really care about keeping it all original. I even considered the possibility of removing my vinyl top and then rolling on some sort of thick epoxy type paint with a heavy napped roller to make it look like vinyl. Then, I ended up just taking the vinyl off and doing a "poor man's" slick top conversion.

[zoomie]

as far as towncars are concerned there were two different options, one had a fiberglass shell, and then there is the reguar roof, which i have and have converted over for a slicktop, its one of those you either love it or hate it things really, i will be finishing up my slicktop project this summer i hope.

[sxcpotatoes]

Are there any pictures around of a slicktop box Merc? The vinyl is cracked to hell and back on one of my '91's (1980c10's old purple-rimmed one I'm putting back together).